http://us63bgjkxwpyrpvsqom6kw3jcy2yujbplkhtzt64yykt42ne2ms7p4yd.onion/graves/news/2019-03-27-firefox_lockbox.html
Your credentials are synced in encrypted form using Firefox Sync. With unreliable, in-browser encryption, I might add. Interaction data. Mozilla receives information about your interaction with Firefox Lockbox, including (1) frequency of editing, viewing, copying, and syncing credentials, (2) whether you are a new or existing Firefox Account user, (3) interactions with Firefox Lockbox menus and icons, (4) length of time the app is in background.